Airports have all kinds of security and safety challenges. Amongst the latest are drones. Around the world, we have seen disruptions at airports in the last year, because someone was flying drones in the restricted airspace. That is reckless and highly dangerous, and while the amount of incidents seems to be indicating that someone is disrupting the airspace on purpose, experts say that most of them are simply “idiots” who don’t know the rules.

The worst impact so far was an annoying and expensive airport shutdown in Gatwick during last year’s Christmas travels. Should a plane ever hit a drone, though, it might end up in a catastrophe. We spoke to a few experts to figure out which approaches there could be to stop drones. Because, as a policeman said after the Gatwick incident: “We could try to shoot them down with a rifle or a shotgun if they come close enough, but these are not very effective methods.” There are other methods on the market, including nets or ballistics, but here we are looking at methods to stop drones without destroying them.

“Drones are an amazing problem”, says Vitaly Mzokov, who heads Kaspersky’s innovation hub which recently launched an Anti-Drone solution. “They have so many benefits, but they have become so inexpensive that you now find lots of inexperienced drone pilots using them.” He agrees that in most cases these interruptions happen not out of malicious intent, but rather because of ignorance. “Often, it’s just a matter of having fun, without thinking how their actions could negatively influence other people.”

Matt Wixey, who leads the Ethical Hacking team at PwC, used ultrasound to stop drones. “Many drones have an ultrasonic altimeter, the same thing as used in submarines and by bats and dolphins. It sends down a pulse that hits an obstacle, bounces back up, and the drone can work out how far away it is from the ground.” Their approach: echo-location jamming. “We kind of blast the drone with sound of the same frequency and it totally messes up the drones navigation system.” So, the drone would either think that it is on the ground or at maximum height and start going up or down. And it becomes completely unresponsive to commands.”

And that is where the weakness of that approach comes in – and why it is not something that can be used in practice. “The issue is that it is really hard to predict whether the drone is going up or going down. You have to be really precise where you interrupt the echolocation – down to microseconds.”

Mzokov’s team is also jamming drones, but they use concentrated radio waves. “The first step is to detect and identify the drones on long distance. If our system figures out that an object is a drone and not a bird, we then create radio noise. That noise disconnects it from the remote control or the GPS signal.” The effect on standard civil drones: they will descend to the ground or stay in the position they were, as that is the safety mechanism when they lose connection. “There are multiple ways to stop drones, but we believe we use the easiest method: confusing the drone to force it out of the danger zone.”

There are other vectors to interfere with drones. “The drone we looked at previously, was basically just a flying Wifi access point”, Matt Wixey recalls. “In the case of drones, even sending legitimate commands is enough to hijack them”, says Eyal Itkin, a Security vulnerability researcher at Check Point Software. “I don’t need to find vulnerabilities; I just need to connect to it. That’s easy for an attacker.”